The present invention relates generally to underground boring tool guidance and, more particularly, to a remote walk over locator/controller configured for determining the underground location of a boring tool and for remotely issuing control commands to a drill rig which is operating the boring tool.
Installing underground utility cable using a steerable boring tool is well known in the art. Various examples are described in U.S. Pat. Nos. 5,155,442, 5,337,002, 5,444,382 and 5,633,589 as issued to Mercer et al (collectively referred to herein as the Mercer Patents), all of which are incorporated herein by reference. An example of the prior art Mercer technique is best illustrated in FIG. 1 herein which corresponds to FIG. 2 in the Mercer Patents. For purposes of clarity, the reference numerals used in the Mercer Patents have been retained herein for like components.
As seen in FIG. 1, an overall boring machine 24 is positioned within a starting pit 22 and includes a length of drill pipe 10, the front end of which is connected to the back end of a steerable boring head or tool 28. As described in the Mercer Patents, the boring tool includes a transmitter for emitting a dipole magnetic field 12 which radiates in front of, behind and around the boring tool, as illustrated in part in FIG. 1. A first operator 20 positioned at the starting pit 22 is responsible for operating the boring machine 24; that is, he or she causes the machine to let out the drill pipe, causing it to push the boring tool forward. At the same time, operator 20 is responsible for steering the boring tool through the ground. A second locator/monitor operator 26 is responsible for locating boring tool 28 using a locator or receiver 36. The boring tool is shown in FIG. 1 being guided beneath an obstacle 30. The locator/monitor operator 26 holds locator 36 and uses it to locate a surface position above tool head 28. Once operator 26 finds this position, the locator 36 is used to determine the depth of tool head 28. Using the particular locator of the present invention, operator 26 can also determine roll orientation and other information such as yaw and pitch. This information is passed on to operator 20 who then may use it to steer the boring tool to its target. Unfortunately, this arrangement requires at least two operators in order to manage the drilling operation, as will be discussed further.
Still referring to FIG. 1, current operation of horizontal directional drilling (HDD) with a walkover locating system requires a minimum of two skilled operators to perform the drilling operation. As described, one operator runs the drill rig and the other operator tracks the progress of the boring tool and determines the commands necessary to keep the drill on a planned course. In the past, communication between the two operators has been accomplished using walkie-talkies. Sometimes hand signals are used on the shorter drill runs. However, in either instance, there is often confusion. Because an operating drill rig is typically quite noisy, the rig noise can make it difficult, if not impossible, to hear the voice communications provided via walkie-talkie. Moreover, both the walkie-talkie and the hand signals are awkward since the operator of the drill rig at many times has both of his hands engaged in operation of the drill rig. Confused steering direction can result in the drill being misdirected, sometimes with disastrous results.
The present invention provides a highly advantageous boring tool control arrangement in which an operator uses a walk-over locator unit that is configured for remotely issuing control commands to a drill rig. In this way, problems associated with reliable communications between two operators are eliminated. In addition, other advantages are provided, as will be described hereinafter.